INTRODUCTION:
CERAMICS:
Ceramics are defined as a products made from inorganic materials having non-metallic properties usually
processed at a high temperature at some time during their manufacture.
The word “ceramics” comes from the Greek word “KERAMOS” meaning “Pottery”,”Potter's Clay”,or “a potter”
-primarily used to mean “Burnt Stuff”.
A ceramic is an inorganic , non-matallic solid prepared by the action of heat and subsequent cooling. Ceramic
materials may have a crystalline or partially crystalline structure or may be amorphous (e.g.-a glass).Because
most common ceramics are crystalline,the definition of ceramic is often restricted to inorganic crystalline
materials, as opposed to the noncrystalline glasses.
The technical definition of ceramics encompasses a much greater variety of products than is normally realized.
To most people, the word ceramics means dinnerware, figurines, vases, and other objects of ceramic art.
The earliest ceramics were pottery objects made from clay,either by itself or mixed with other materials,
hardened in fire. Later ceramics were glazed and fired to produce a colored, smooth surface. Ceramics now
include domestic, industrial and building products and art objects.
The majority of ceramic products is not generally recognized as such
“ceramic” may be used as an adjective describing a material, products or process; or as a singular noun, or,
more commonly, as a plural noun, “ceramics”.
SANITARY WARE:
Sanitaryware encompasses all plumbed-in ceramic bathroom fixtures. Sanitaryware therefore includes sinks,
bathroom basins, toilets, wc's, bidets. The word sanitaryware conjure up images of clean, pristine, ceramics
with soft curves and angular edges.
They are considered to be extremely durable as well as hygienic. The manufacture of ceramic sanitaryware is now
a highly automated process with thousands of pieces per week being produced in factories all around the world.
Washbasin, toilets and bidets are all considered standard sanitaryware pieces but each manufacturer has his own
range of designs. This can includes articles of different size, shapes, color and finish. Manufacturing Process-
1. Raw materials
2. Moulding
3. Slip preparation
4. Casting
5. Drying
6. Glazing
7. Firing
8. Inspection and packing
1. RAW MATERIALS-
Raw materials for body includes-feldspar, quartz, soapstone, barium, soda ash, silicates, china clay, ball clay,
water etc.
Raw materials for glaze includes-feldspar, quartz, calcite, zirconium, barium oxide, zinc oxide, china clay,
soapstone, cobalt (white paste), water, limestone.
Plaster of paris is the material that is used for modeling and moulding of the ceramics sanitaryware.
Although silica is the most commonest constituents of the earth's crust, the study of it and it's compounds
baffled investigators for many decades. There are several reasons for this-
Firstly, silicates are almost all insoluble in anything except hydrofluoric acid, so that they can not be
separated or investigated by solution methods.
Secondly, their thermal reactions of transition, inversion, melting or freezing are sluggish and ill- defined so
that no information about compounds and their purity can be inferred from thermal curves.
Thirdly, the distinctions between compounds and solid solutions and mixture are not clear and phase diagrams are
more difficult to plot than usual.
Clays occur in deposites of greatly varying nature in many parts of the world. No two deposits have exactly the
same clay and frequently different samples of clay from the same deposit differ. It is therefore worth while to
give brief consideration to the origin and mineralogy of clay. Firstly, clay is a secondary rock, that is, it
has been formed by weathering of certain other rocks. Secondly, clay is a mixture.
BALL CLAY-
These are sedimentary plastic clays which are dark in the unfired state because of organic impurities but burn
white or cream coloured as long as they are not vitrified fully. They have a large proportion of kaolinite but
also contain a variety of impurities and probably have some montmorillonite attached to the edges of the
kaolinite platelets. The name is derived from the English mining method of cutting the clay out in cubes or
balls.
There are three important English deposits of ball clays in Dorset, North Devon and South Devon. In the United
State they occur in Florida, Tennessee, Kentucky, Alabatna and New Jersey.
Ball clays are used in white wares(earthenware, porclain, etc.) To make the body plastic and workable.
CHINA CLAY
Kaolinite is a clay mineral, part of the group of industrial minerals, with the chemical composition
Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one
octahedral sheet of alumina octahedra. Rocks that are rich in kaolinite are known as china clay, white clay, or
kaolin.
The name is derived from Chinese:; pinyin: Gaoling or Kao-ling ("High Hill") in Jingdezhen, Jiangxi province,
China. The name entered English in 1727 from the French version of the word: "kaolin", following Francois Xavier
d'Entrecolles's reports from Jingdezhen.
Kaolinite has a low shrink-swell capacity and a low cation exchange capacity (1-15 meq/100g). It is a soft,
earthy, usually white mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of
aluminium silicate minerals like feldspar. In many parts of the world, it is colored pink-orange-red by iron
oxide, giving it a distinct rust hue. Lighter concentrations yield white, yellow or light orange colours.
Alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, USA.
FELDSPAR-
Feldspars (KAlSi3O8 , NaAlSi3O8, CaAl2Si2O8) are a group of rock-forming tectosilicate minerals which make up
as much as 60% of the Earth's crust.3O8
Feldspars crystallize from magma in both intrusive and extrusive igneous rocks, as veins, and are also present
in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar (see below) is
known as anorthosite. Feldspars are also found in many types of sedimentary rock.
Compositions
This group of minerals consists of framework tectosilicates. Compositions of major elements in common feldspars
can be expressed in terms of three endmembers:
Potassium-Feldspar (K-spar) endmember KAlSi3O8
Albite endmember NaAlSi3O8
Anorthite endmember CaAl2Si2O8
Solid solutions between K-feldspar and albite are called alkali feldspar. Solid solutions between albite and
anorthite are called plagioclase or more properly plagioclase feldspar. Only limited solid solution occurs
between K-feldspar and anorthite, and in the two other solid solutions, immiscibility occurs at temperatures
common in the crust of the earth. Albite is considered both a plagioclase and alkali feldspar. In addition to
albite, barium feldspars are also considered both alkali and plagioclase feldspars. Barium feldspars form as the
result of the replacement of potassium feldspar.
QUARTZ-
Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a
continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra,
giving an overall formula SiO2.
There are many different varieties of quartz, several of which are semi-precious gemstones. Especially in Europe
and the Middle East, varieties of quartz have been since antiquity the most commonly used minerals in the making
of jewelry and hardstone carvings.
The word "quartz" is derived from the German word "quarz" and its Middle High German ancestor "twarc", which
probably originated in Slavic (cf. Czech tvrdý ("hard"), Polish twardy hard.
Crystal habit and structure).
Crystal structure of α-quartz and β-quartz
Quartz belongs to the trigonal crystal system. The ideal crystal shape is a six-sided prism terminating with
six-sided pyramids at each end. In nature quartz crystals are often twinned, distorted, or so intergrown with
adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal
faces altogether and appear massive. Well-formed crystals typically form in a 'bed' that has unconstrained
growth into a void, but because the crystals must be attached at the other end to a matrix, only one termination
pyramid is present. A quartz geode is such a situation where the void is approximately spherical in shape, lined
with a bed of crystals pointing inward.
SOAPSTONE-
Soapstone (also known as steatite or soaprock) is a metamorphic rock, a talc-schist. It is largely composed of
the mineral talc and is thus rich in magnesium. It is produced by dynamothermal metamorphism and metasomatism,
which occurs in the areas where tectonic plates are subducted, changing rocks by heat and pressure, with influx
of fluids, but without melting. It has been a medium for carving for thousands of years.
Soapstone is sometimes used for fireplace surrounds and woodstoves, because it can absorb and evenly distribute
heat while being easy to manufacture. It is also used for counter tops. A weathered or aged appearance will
occur naturally over time as the patina is enhanced. Applying mineral oil simply darkens the appearance of the
stone; it does not protect it in any way.
Soapstone can be used to create molds for casting objects from soft metals, such as pewter or silver. The soft
stone is easily carved and is not degraded by heating. The slick surface of
soapstone allows the finished object to be easily removed.
The term steatite is sometimes used for soapstone. It is often used as an insulator or housing for electrical
components, due to its durability and electrical characteristics and because it can be pressed into complex
shapes before firing. Steatite undergoes transformations when heated to temperatures of 1000-1200℃ into
enstatite and cristobalite; in the Mohs scale, this corresponds to an increase in hardness from 1 to 5.5-6.5.
BARIUM-
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft
silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity
with air. Its oxide is historically known as baryta but it reacts with water and carbon dioxide and is not found
as a mineral. The most common naturally occurring minerals are the very insoluble barium sulfate, BaSO4
(barite), and barium carbonate, BaCO3 (witherite). Barium's name originates from Greek barys (βαρύς), meaning
"heavy", describing the high density of some common barium-containing ores.
Barium has few industrial applications, but the metal has been historically used to scavenge air in vacuum
tubes. Barium compounds impart a green color to flames and have been used in fireworks. Barium sulfate is used
for its density, insolubility, and X-ray opacity. It is used as an insoluble heavy mud-like paste when drilling
oil wells, and in purer form, as an X-ray radiocontrast agent for imaging the human gastrointestinal tract.
Soluble barium compounds are poisonous due to release of the soluble barium ion, and have been used as
rodenticides. New uses for barium continue to be sought. It is a component of some "high temperature" YBCO
superconductors, and electroceramics.
Characteristics-
Physical properties
Barium is a soft, silvery white alkali earth metal, which quickly oxidizes in air. It crystallizes in body
centered cubic lattices. It burns with a green to pale green flame, resulting from emission at 524.2 and 513.7
nm. Its simple compounds are notable for their relatively high (for an alkaline earth element) specific gravity.
This high density is true of the most common barium-bearing mineral, barite (BaSO4), also called 'heavy spar'
due to the high density (4.5 g/cm³).
Chemical properties
Barium, as for other alkali earth (group II) metals, is highly reducing. It reacts exothermically with oxygen at
room temperature to form barium oxide and peroxide. Because of its sensitivity to air, samples are generally
stored under protective oils. The reaction is violent if barium is powdered. The metal is readily attacked in
most acids, with the notable exception of sulfuric acid, as passivation stops the reaction by forming the
insoluble barium sulfate.
It also reacts violently with water according to the reaction:
Ba + 2H2O→ Ba(OH)2 + H2↑
Barium combines with several metals, including aluminium, zinc, lead and tin, forming intermetallic phases and
alloys.
SODIUM CARBONATE-
Sodium carbonate (also known as washing soda or soda ash), Na2CO3 is a sodium salt of carbonic acid. It most
commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the
monohydrate. Sodium carbonate is domestically well known for its everyday use as a water softener. It can be
extracted from the ashes of many plants. It is synthetically produced in large quantities from table salt and
limestone in a process known as the Solvay process.
Uses:
The manufacture of glass is one of the most important uses of sodium carbonate. When combined with silica (SiO2)
and calcium carbonate (CaCO3) and heated to high temperatures, then cooled rapidly, glass is produced. This type
of glass is known as soda lime glass.
In chemistry, it is often used as an electrolyte. This is because electrolytes are usually salt-based, and
sodium carbonate acts as a very good conductor in the process of electrolysis. Additionally, unlike chloride
ions which form chlorine gas, carbonate ions are not corrosive to the anodes. It is also used as a primary
standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately.
In domestic use, it is used as a water softener during laundry. It competes with the ions magnesium and calcium
in hard water and prevents them from bonding with the detergent being used. Without using washing soda,
additional detergent is needed to soak up the magnesium and calcium ions. Called Washing Soda, Soda crystals or
Sal Soda[3] in the detergent section of stores, it effectively removes oil, grease, and alcohol stains. Sodium
carbonate is also used as a descaling agent in boilers such as found in coffee pots, espresso machines,etc.
In dyeing with fiber-reactive dyes, sodium carbonate (often under a name such as soda ash fixative or soda ash
activator) is used to ensure proper chemical bonding of the dye with the fibers, typically before dyeing (for
tie dyes), mixed with the dye (for dye painting), or after dyeing (for immersion dyeing).
Sodium carbonate is a powerful electrolyte, and is therefore used to speed up the decomposition of water in
electrolysis.
SILICATES-
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but
hexafluorosilicate (SiF62-) and other anions are also included. This article focuses mainly on the Si-O
anions. Silicates comprise the majority of the earth's crust, as well as the other terrestrial planets, rocky
moons, and asteroids. Sand, Portland cement, and thousands of minerals are examples of silicates.
Silicate compounds, including the minerals, consist of silicate anions whose charge is balanced by various
cations. Myriad silicate anions can exist, and each can form compounds with many different cations. Hence this
class of compounds is very large. Both minerals and synthetic materials fit in this class.
Structural principles
In the vast majority of silicates, including silicate minerals, the Si occupies a tetrahedral environment, being
surrounded by 4 oxygen centres. In these structures, the chemical bonds to silicon conform to the octet rule.
These tetrahedra sometimes occur as isolated SiO44- centres, but most commonly, the tetrahedra are joined
together in various ways, such as pairs (Si2O76-) and rings (Si6O1812-). Commonly the silicate anions are
chains, double chains, sheets, and three-dimensional frameworks. All such species have negligible solubility in
water at normal conditions...
WATER-
Water is a chemical substance with the chemical formula H2O. Its molecule contains one oxygen and two hydrogen
atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with
its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near
hydrophilic surfaces.
Water covers 70.9% of the Earth's surface,[3] and is vital for all known forms of life. On Earth, it is found
mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air
as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Oceans hold
97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and
ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured
products.
Water on Earth moves continually through a cycle of evaporation or transpiration (evapotranspiration),
precipitation, and runoff, usually reaching the sea. Over land, evaporation and transpiration contribute to the
precipitation over land.
CALCITE-
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The other polymorphs
are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470℃, and vaterite is even
less stable.
Properties
Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals.
However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms,
or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms. It may
occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the
rhombohedron form. Its fracture is conchoidal, but difficult to obtain.
It has a defining Mohs hardness of 3, a specific gravity of 2.71, and its luster is vitreous in crystallized
varieties. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or
even black can occur when the mineral is charged with impurities.
Calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent
variety called Iceland spar is used for optical purposes. Acute scalenohedral crystals are sometimes referred to
as "dogtooth spar" while the rhombohedral form is sometimes referred to as "nailhead spar".
ZIRCONIUM-
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the
mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles
titanium. Zirconium is mainly used as a refractory and opacifier, although minor amounts are used as alloying
agent for its strong resistance to corrosion. Zirconium is obtained mainly from the mineral zircon, which is the
most important form of zirconium in use.
Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene
dichloride, respectively. Five isotopes occur naturally, three of which are stable. Zirconium compounds have no
biological role.
Characteristics
Zirconium is a lustrous, grayish-white, soft, ductile, and malleable metal which is solid at room temperature,
though it becomes hard and brittle at lower purities. In powder form, zirconium is highly flammable, but the
solid form is far less prone to ignition. Zirconium is highly resistant to corrosion by alkalies, acids, salt
water, and other agents. However, it will dissolve in hydrochloric and sulfuric acid, especially when fluorine
is present. Alloys with zinc become magnetic below 35 K.
Zirconium's melting point is 1855℃ (3371 °F), and its boiling point is 4371℃ (7900 °F). Zirconium has an
electronegativity of 1.33 on the Pauling scale. Of the elements within d-block, zirconium has the fourth lowest
electronegativity after yttrium, lutetium, and hafnium.
ZINC-
Zinc , or spelter (which may also refer to zinc alloys), is a metallic chemical element; it has the symbol Zn
and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects,
chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2.
Zinc is the 24th most abundant element in the Earth's crust and has five stable isotopes. The most exploited
zinc ore is sphalerite, a zinc sulfide. The largest exploitable deposits are found in Australia, Asia, and the
United States. Zinc production includes froth flotation of the ore, roasting, and final extraction using
electricity (electrowinning).
Zinc is an essential mineral of "exceptional biologic and public health importance". Zinc deficiency affects
about two billion people in the developing world and is associated with many diseases. In children it causes
growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea, contributing to the death
of about 800,000 children worldwide per year. Enzymes with a zinc atom in the reactive center are widespread in
biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and
copper deficiency.
Characteristics
Zinc, also referred to in nonscientific contexts as spelter, is a bluish-white, lustrous, diamagnetic metal,
though most common commercial grades of the metal have a dull finish. It is somewhat less dense than iron and
has a hexagonal crystal structure.
The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C. Above 210℃,
the metal becomes brittle again and can be pulverized by beating. Zinc is a fair conductor of electricity. For a
metal, zinc has relatively low melting (419.5℃, 787.1 F) and boiling points (907℃). Its melting point is the
lowest of all the transition metals aside from mercury and cadmium.
COBALT-
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically
combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
Cobalt is used in the preparation of magnetic, wear-resistant and high-strength alloys. Cobalt silicate and
cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, smalt, ceramics, inks,
paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially
important radioisotope, used as a radioactive tracer and in the production of gamma rays.
Cobalt is the active center of coenzymes called cobalamin or vitamin B12, and is an essential trace element for
all animals. Cobalt is also an active nutrient for bacteria, algae and fungi.
Characteristics
A block of electrolytically refined cobalt (99.9% purity) cut from a large plate
Cobalt is a ferromagnetic metal with a specific gravity of 8.9. Pure cobalt is not found in nature, but
compounds of cobalt are common. Small amounts of it are found in most rocks, soil, plants and animals. The Curie
temperature is 1115℃ and the magnetic moment is 1.6-1.7 Bohr magnetons per atom. In nature, it is
frequently associated with nickel, and both are characteristic minor components of meteoric iron. Cobalt has a
relative permeability two thirds that of iron.Metallic cobalt occurs as two crystallographic structures: hcp
and fcc. The ideal transition temperature between the hcp and fcc structures is 450℃, but in practice, the
energy difference is so small that random intergrowth of the two is common.
Cobalt is a weakly reducing metal that is protected from oxidation by a passivating oxide film. It is attacked
by halogens and sulfur. Heating in oxygen produces Co3O4 which loses oxygen at 900℃ to give the monoxide CoO.
2. MOULDING-
Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model
called a pattern.
A mold or mould is a hollowed-out block that is filled with a liquid like plastic, glass, metal, or ceramic raw
materials. The liquid hardens or sets inside the mold, adopting its shape. A mold is the opposite of a cast. The
manufacturer who makes the molds is called the moldmaker. A release agent is typically used to make removal of
the hardened/set substance from the mold easier.
The terminology can depend on the application. Sand casting involves both a "pattern" (which is the
positive-image model of the desired part) and a "mold" (which is the negative-image hole made by packing sand
around the pattern).
Types of molding include:
• Blow molding
• Compaction plus sintering
• Compression molding
• Expandable bead molding
• Extrusion molding
• Foam molding
• Injection molding
• Laminating
Blow molding
Blow molding (also known as blow moulding or blow forming) is a manufacturing process by which hollow plastic
parts are formed. In general, there are three main types of blow molding: extrusion blow molding, injection blow
molding, and stretch blow molding. The blow molding process begins with melting down the plastic and forming it
into a parison or preform. The parison is a tube-like piece of plastic with a hole in one end in which
compressed air can pass through.
The parison is then clamped into a mold and air is pumped into it. The air pressure then pushes the plastic out
to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected.
Compaction plus sintering
Compaction may refer to:
• Soil compaction, for mechanically induced compaction near the ground surface
• Compaction (geology), part of the process of lithification involving mechanical dewatering of a sediment by
progressive loading under several km of geomaterial.
• Waste compaction, related to garbage
• Cold compaction, powder compaction at low temperatures
• Data compaction, related to computers
• Curve-fitting compaction
• Compactor, a device that performs compaction
• Compaction, a process during early embryogenesis, which occurs during the cleavage stage of human
embryogenesis
Sintering is a method for making objects from powder, by heating the material in a sintering furnace[1] below
its melting point (solid state sintering) until its particles adhere to each other. Sintering is traditionally
used for manufacturing ceramic objects, and has also found uses in such fields as powder metallurgy. A simple
example of sintering can be observed when icecubes in a glass of water adhere to each other.
General sintering
Control of temperature is very important to the sintering the process, since grain-boundary diffusion and volume
diffusion rely heavily upon temperature, the size and distribution of particles of the material, the materials
composition, and often the sintering environment to be controlled.
Compression molding
Compression molding is a method of molding in which the molding material, generally preheated, is first placed
in an open, heated mold cavity. The mold is closed with a top force or plug member, pressure is applied to force
the material into contact with all mold areas, while heat and pressure are maintained until the molding material
has cured. The process employs thermosetting resins in a partially cured stage, either in the form of granules,
putty-like masses, or preforms. Compression molding is a high-volume, high-pressure method suitable for molding
complex, high-strength fiberglass reinforcements. Advanced composite thermoplastics can also be compression
molded with unidirectional tapes, woven fabrics, randomly oriented fiber mat or chopped strand. The advantage of
compression molding is its ability to mold large, fairly intricate parts. Also, it is one of the lowest cost
molding methods compared with other methods such as transfer molding and injection molding; moreover it wastes
relatively little material, giving it an advantage when working with expensive compounds. However, compression
molding often provides poor product consistency and difficulty in controlling flashing, and it is not suitable
for some types of parts. Fewer knit lines are produced and a smaller amount of fiber-length degradation is
noticeable when compared to injection molding. Compression-molding is also suitable for ultra-large basic shape
production in sizes beyond the capacity of extrusion techniques. Materials that are typically manufactured
through compression molding include: Polyester fiberglass resin systems (SMC/BMC), Torlon, Vespel,
Poly(p-phenylene sulfide) (PPS), and many grades of PEEK.
Extrusion molding
Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn
through a die of the desired cross-section. The two main advantages of this process over other manufacturing
processes are its ability to create very complex cross-sections and work materials that are brittle, because the
material only encounters compressive and shear stresses. It also forms finished parts with an excellent surface
finish.
Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing
many pieces). The extrusion process can be done with the material hot or cold.
Commonly extruded materials include metals, polymers, ceramics, concrete and foodstuffs.
Process
The process begins by heating the stock material (for hot or warm extrusion). It is then loaded into the
container in the press. A dummy block is placed behind it where the ram then presses on the material to push it
out of the die. Afterward the extrusion is stretched in order to straighten it. If better properties are
required then it may be heat treated or cold worked.
The extrusion ratio is defined as the starting cross-sectional area divided by the cross-sectional area of the
final extrusion. One of the main advantages of the extrusion process is that this ratio can be very large while
still producing quality parts.
Hot extrusion temperature for various metals
Material Temperature → [℃ (°F)]
Magnesium → 350-450 (650-850)
Aluminium → 350-500 (650-900)
Copper → 600-1100 (1200-2000)
Steel → 1200-1300 (2200-2400)
Titanium → 700-1200 (1300-2100)
Nickel → 1000-1200 (1900-2200)
Refractory alloys up to → 2000 (4000)
The extrusion process is generally economical when producing between several kilograms (pounds) and many tons,
depending on the material being extruded. There is a crossover point where roll forming becomes more economical.
For instance, some steels become more economical to roll if producing more than 20,000 kg (50,000 lb).
Injection molding
Injection molding (British English: moulding) is a manufacturing process for producing parts from both
thermoplastic and thermosetting plastic materials. Material is fed into a heated barrel, mixed, and forced into
a mold cavity where it cools and hardens to the configuration of the mold cavity.[1] After a product is
designed, usually by an industrial designer or an engineer, molds are made by a moldmaker (or toolmaker) from
metal, usually either steel or aluminum, and precision-machined to form the features of the desired part.
Injection molding is widely used for manufacturing a variety of parts, from the smallest component to entire
body panels of cars.
Applications
Injection molding is used to create many things such as wire spools, packaging, bottle caps, automotive
dashboards, pocket combs, some musical instruments (and parts of them), one-piece chairs and small tables,
storage containers, mechanical parts (including gears), and most other plastic products available today.
Injection molding is the most common method of part manufacturing. It is ideal for producing high volumes of the
same object.[5] Some advantages of injection molding are high production rates, repeatable high tolerances, the
ability to use a wide range of materials, low labor cost, minimal scrap losses, and little need to finish parts
after molding. Some disadvantages of this process are expensive equipment investment, potentially high running
costs, and the need to design moldable parts.
Laminating
A laminate is a material that can be constructed by uniting two or more layers of material together. The process
of creating a laminate is lamination, which in common parlance refers to the placing of something between layers
of plastic and gluing them with heat and/or pressure, usually with an adhesive. However, in electrical
engineering, lamination is a construction technique used to reduce unwanted heating effects due to eddy currents
in components, such as the magnetic cores of transformers.
Types of laminators
Three types of laminators are used most often in digital imaging:
• Pouch laminators
• Heated roll laminators
• Cold roll laminators
Film types
Laminate film is generally categorized into these five categories:
• Standard thermal laminating films
• Low-temperature thermal laminating films
• Heatset (or heat-assisted) laminating films
• Pressure-sensitive films
• Liquid laminate.
3. SLIP PREPARTION-
SELECTION OF MATERIALS
Selection of the starting raw ceramic materials is crucial. It isvirtually impossible to obtain the optimum
properties if the powders orgrain do not have the right characteristics. Both fine and coarse materialswill be
discussed.Fine Grained PowdersFour attributes of powders will be discussed in relation to theselection of
materials. These are particle size distribution, shape, purity,and flaw sources. Particle Size DistributionThere
are two conflicting consequences to particle size in thisrange ( 0.1-5.0 µm). These are sinterability and
processing characteristics.Very fine particles have a high surface area that can be used to lowersintering
temperatures, increase fired density, and produce a small grainsize in the fired ceramic. These ceramics are
wear resistant and strong.Toward the lower end of the range, the amount of surface makes thesepowders strongly
influenced by absorbed materials and inter particulateforces. They become difficult to process and result in a
low green densityand a high firing shrinkage. The surface area is much lower toward the upper end of the
sizerange.. This requires a higher firing temperature, a lower firing density,and a coarser grain when fired.
These ceramics are easier to process sincesurface effects are much less. Typically, the green density is higher
and thefiring shrinkage is less. Alumina, in the upper part of the size range, canhave a glassy bonding phase.In
the lower middle of the range (0.3-0.6 µm), a compromise isreached where processing is manageable. Sintering
temperatures arerelatively low, firing shrinkage is fair, fired density is near theoretical, andgrain size in
the ceramic is small (1-3 µm).
BALL MILL
A ball mill is a type of grinder used to grind materials into extremely fine powder for use in mineral dressing
processes, paints, pyrotechnics, and ceramics.
A ball mill, a type of grinder, is a cylindrical device used in grinding (or mixing) materials like ores,
chemicals, ceramic raw materials and paints. Ball mills rotate around a horizontal axis, partially filled with
the material to be ground plus the grinding medium. Different materials are used as media, including ceramic
balls, flint pebbles and stainless steel balls. An internal cascading effect reduces the material to a fine
powder. Industrial ball mills can operate continuously, fed at one end and discharged at the other end. Large to
medium-sized ball mills are mechanically rotated on their axis, but small ones normally consist of a cylindrical
capped container that sits on two drive shafts (pulleys and belts are used to transmit rotary motion). A rock
tumbler functions on the same principle. Ball mills are also used in pyrotechnics and the manufacture of black
powder, but cannot be used in the preparation of some pyrotechnic mixtures such as flash powder because of their
sensitivity to impact. High-quality ball mills are potentially expensive and can grind mixture particles to as
small as 5 nm, enormously increasing surface area and reaction rates. The grinding works on the principle of
critical speed. The critical speed can be understood as that speed after which the steel balls (which are
responsible for the grinding of particles) start rotating along the direction of the cylindrical device; thus
causing no further grinding.
4. CASTING-
Casting is a manufacture process by which a liquid material is usually poured into a mould, which contains a
hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a
casting, which is ejected or broken out of the mold to complete the process.
Various methods of casting are used depending on the shape of the piece and the volume of production required.
Traditionally, bench casting was done by skilled casters who manually controlled the filling of the mould using
a type of liquid gun. In more recent years the casting has been fully automated and moulds are filled
automatically with liquid slip at high pressure(pressure casting) or low pressure(beam casting). After the
appropriate casting time excess slip is removed from the mould. The clay pieces complete their solidification
before they are removed as damp clay articles ready for drying.
There are two methods for casting-
1. Slip casting
2. Pressure casting
1. SLIP CASTING-
Slip casting is a technique for the mass production of pottery, especially for the shapes not easily made on a
wheel. A liquid clay body slip(usually mixed in a blunger) is poured into microporous plaster of paris mold. The
porous nature of the mold provides a capillary suction pressure of ≈0.1-0.2mpa, which draws the liquid from the
slurry into the mold. The origin of the capillary suction pressure is similar to that of capillary rise. A
consolidated layer of solids, referred to as: cast or cake, forms on the walls of the mold. After a sufficient
thickness of the cast is formed , the surplus slip is poured out and the mold and cast are allowed to dry.
Normally, the cast shrinks away from the mold during the drying process and can be easily removed. Following
binder burnout, the cast is fired to produce the final article.
Slip Casting Mechanics-
The flow of liquid through a porous medium is described by darcy' law which, in one dimension can be written as-
J=K(dp/dx)/ηL
Where J is the flux of liquid, dp/dx is the pressure gradient in the liquid, ηL is the viscosity of the liquid,
and K is the permeability of the porous medium.
After integrating this equation and applying the appropriate boundary condition, Tiller and Tsai found that the
thickness of the consolidated layer is related to the time of casting by the equation-
L²=2Hpt/ηL --------- (*)
The function H depends on the properties of both the consolidated layer and the mold.
2. PRESSURE CASTING-
a generic method which includes all methods of infiltrating a perform involving the application of hydrostatic
pressure to the infiltrating liquid. pressure is usually required because of viscosity related flow limitations.
this process similar to injection molding, is a variant of porous mold casting in which the ceramic suspension
is injected into the mold under high pressure. the mold may be fabricated from plastic, plaster or ceramic.
equation indicates that for a given slurry, as the filtration pressure p increases, the time taken to produce a
given thickness of cast, L, decreases. the casting can be speeded up by the application of an external pressure
to the slurry. this is the principle of pressure casting, also referred to as pressure filtration. the plaster
of paris molds used in slip casting are, however, weak and cannot withstand pressures greater than≈0.5MPa.
plastic or metal molds must be used in pressure casting. particles in the slurry form a consolidated layer (the
cast) on the filter as the liquid is forced through the system. compared to the filter, the cast provides a much
greater resistance to flow of the liquid.
5. DRYING-
Drying is a mass transfer process consisting of the removal of water or another solute [1] by evaporation from a
solid, semi-solid or liquid. The solute to be removed is almost always water, especially so in bioproducts like
food, grains, and pharmaceuticals like vaccines. However, if it is not water, it is typically still a substance
which is a liquid at room temperature. This process is often used as a final production step before selling or
packaging products, so the substance that is dried will hereforth be referred to as the product. To be
considered "dried", the final product must be solid, in the form of a continuous sheet (e.g. paper), long pieces
(e.g. wood), particles (e.g. cereal grains like corn flakes) or powder (e.g. sand, salt, washing powder, milk
powder). A source of heat, and way to removed the vapor produced by the process are necessary. In bioproducts
like food, grains, and pharmaceuticals like vaccines, the solvent to be removed is almost invariably water.
DRYERS
BELT DRYERS
A belt dryer is an apparatus which is used for continuous drying and cooling of pellets, pastes, moulded
compounds and panels using air, inert gas, or flue gas.
Working principle
A Belt dryer / Belt cooler is a device designed for the particularly gentle thermal treatment of product. The
wet product is continuously and evenly applied through an infeed chamber onto a perforated belt. The belt,
predominantly in horizontal position, carries the product through the drying area which is divided into several
sections. In these cells drying gas flows through or over the wet product and dries it. Each cell can be
equipped with a ventilating fan and a heat exchanger. This modular design allows the drying and cooling
temperatures to be controlled separately in the different sections. Thus, each dryer cell can be individually
controlled and the drying / cooling air flow can be varied in each cell. In addition, the speed of the conveyor
belt can be varied what gives an additional parameter for setting of drying time. The cells can be heated or
cooled directly or indirectly, and all heating media, such as oil, steam, hot water or hot gas can be used.
6. GLAZING-
The raw materials required for glazing process are known as batch composition. In batch composition some
compounds are used as it is, and some are fritted before using. Those compounds that are water soluble are
fritted with certain amount of alumina and silica to give insoluble aluminosilicates before grinding.
Basic raw materials and their percent for traditional sanitary ware industries are given below-
Feldspar
Quartz
Calcite
Zirconium
Barium
Zinc
China clay
Soap stone
Water
Specific raw materials for glazing process-
Colouring material is the specific raw material in glazing. For every colour the percentage of colouring
material is different.
These are as follows-
Ivory→ 1.5%
Blue→ 2%
Pink→ 2.5%
Green→ 3.5%
Grey→ 2%
Magenta→ 6%
Black→ 5.5%
Red brown→ 3.15%
Desired properties of glazes-
1. Fusibility must be such that maximum liquid glass is formed at the desired maturing temperature.
2. Viscosity should be moderate at peak firing temperature, so that surfaces even out but no over all flow
occurs down inclined or vertical surfaces.
3. Surface tension shouls be low to avoid crawling.
4. Volatization of glazes components during firing should be minimized.
5. Reaction with the body should be moderate to give good fit without too much change in composition of either
glazes or body.
6. Absorption into the body of glaze constituents or eutectic formed during firing should not occur.
7. Devitrification should not occur in transparent glossy glazes.
8. Expansion coefficient and young'modulus of elasticity should relate to those of the body in such a way that
maximum strength achieved.
9. Homogeneity, smoothness and hardness to resist abrasion, scratching.
10. Chemical durability.
11. Colour for aesthetic or thermal reasons.
12. Electrical properties e.g.-low power factor.
7. FIRING-
We applied the firing process after glazing . glazing property of ceramic body .its essential that every body
has homogeneously glazed when glazing are distributed homogenously then increasing the physical and mechanical
strength.
Ceramic ware must by definition undergo at least 1 firing , which converts the shaped were irreversibly into a
hard product , resistant to water and chemicals . unglazed ware is fired only once.
Glazed were is traditionally fired twice .firstly the biscuit firing when all bodies except hard pocelian are
fully matured ..the biscuit ware is then glazed glossed fired at a low temperature, for glazed to mature .in the
case of hard policelain are fully matured the body ,a porus article is produced.
Factor due to body composition
1 removal of free ,hygroscopic and combined water
2 combustion and removal of organic waste
3 combustion and removal of sulphurious waste
4 reduction or oxidation of body constituents
5 gradual volume changes
6 maturing temperature
7 sudden volume changes due to inversion during both heating and cooling
Factors Due to Body Preparation
1 grain sizes of constituents
2 Geometry ware
3 permeability to escaping gas heat conductivity and elasticity at different temperature
Factor due to firing Methods
1 Time and heat needed to heat up the kiln structure and furniture
2 Time and lag between first and last pieces of the settling
To attain a given temperature
3 Controbility of heating method
8. INSPECTION and PACKING-
1 INTRODUCTION-
The ceramic tiles industrial sector is a relatively young industry which has taken significantadvantage of the
strong evolution in the world of automation in recent years. All production phases
have been addressed through various technical innovations, with the exception of the final stage of
themanufacturing process. This is still performed manually and is concerned with visual surface inspectionin
order to sort tiles into distinct categories or to reject those found with defects and pattern faults. This
paper addresses the problem of defects and pattern faults by automatic inspection and we review a numberof
techniques developed to detect various defects in plain and textured tiles.
2 SANITARY WARES DEFECTS-
The inspection for defect detection has to be carried out at considerable rates of the order of twotiles per
second. The objective of inspection is tile classification on the basis of two parameters, namelydefects and
colour grading. Depending on the number of defects and their dimensions, the tiles are
grouped into:
- First Class (none or very few acceptable defects)
- Second Class (few but still acceptable defects)
- Waste (unacceptable defects)
Some of the most common and anti-aesthetic defects found on both plain and textured tiles canbe categorised as
cracks, bumps, depressions, pin-holes, dirt, drops, ondulations, and colour and texturedefects.
RESULTS-
The tiles used in our experiments are of size 200 200mm and are either plain or textured. The colours of plain
or textured tiles are expected to span a wide range. In the images shown in this paper,some defects may not be
easily visible and we have randomly encircled some of them for saliency. In mostdefect images a dilation
operation is carried out to enhance the results. All detected faults correspond totrue faults.
• Short and long cracks
We had no examples of tiles with real defects of such nature, so we superimposed such defects onimages of real
tiles to exemplify the power of our algorithm.
• Water Drops and Ondulations
It show the application of the chromato-structural defect detection algorithmto plain white tiles with water
drop and ondulation defects.
• Colour
It contains a spot-like colour abnormality besides the obvious large blobdefect. This spot defect was also
detected at the time of colourcategory classification when it was rejected as a colour not identified during the
training process.
SUMMARY AND CONCLUSIONS-
The automation of the inspection stage will play a crucial role in advancing the development of theceramic tile
manufacturing process. In this paper we have shown a number of techniques developed for the detection of a
multifarious range of ceramic tile defects.
We described optimal spot and line detectors used independently and as post-processing stages to our other
techniques. The Wigner distribution used for crack detection is effectively the Fourier transformation of a
non-linear function of the tile image function. It is a very accurate approach but
it is computationally demanding. We have considered alternative and faster methods which will be reported soon.
We also presented a framework for the detection of defects in randomly textured images based on their colour and
texture information. Also, the approach has addressed the problem of colour segmentation as a by-product.
It is hoped that the considerable advance achieved in overall production through the automation of ceramic tile
inspection will eliminate an estimated 70-80% customer complaint rate regarding product quality.Furthermore, the
spin-offs of the findings of this project can have an impact in other industrial
fields presenting similar problems; for instance in the textile industry for defect detection, loose threads
detection, and colour shading classification on fabrics, the agro-food industry for visual analysis of crops such
as apples/oranges/pears/etc, the wood industry for texture and colour classification, and in a number of other
industries.